We have searched for the lepton-flavor-violating decay $B^0\to K^{*0}{\mu }^{\pm }{e}^{\mp }$ using a data sample of $711{\mathrm{fb}}^{-1}$ that contains $772\times {10}^6$ $B\overline{B}$ pairs. The data were collected near the $\mathrm{\Upsilon }(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. No signals were observed, and we set 90% confidence level upper limits on the branching fractions of $\mathcal{B}(B^0\to K^{*0}{\mu }^{+}{e}^{-})<1.2\times {10}^{-7}$, $\mathcal{B}(B^0\to K^{*0}{\mu }^{-}{e}^{+})<1.6\times {10}^{-7}$, and, for both decays combined, $\mathcal{B}(B^0\to K^{*0}{\mu }^{\pm }{e}^{\mp })<1.8\times {10}^{-7}$. These are the most stringent limits on these decays to date.

• Received 10 July 2018

DOI:https://doi.org/10.1103/PhysRevD.98.071101

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society